U.S. patent number 6,769,844 [Application Number 09/757,996] was granted by the patent office on 2004-08-03 for cutting insert and method of making the same.
This patent grant is currently assigned to Kennametal Inc.. Invention is credited to James M. Waggle.
United States Patent |
6,769,844 |
Waggle |
August 3, 2004 |
Cutting insert and method of making the same
Abstract
A cutting insert comprises a rake face, a plurality of flank
faces including clearance faces having a positive clearance angle.
A cutting edge is formed at an intersection between the rake faces
and the flank face and a convex wiper cutting edge formed on the
cutting edge. A method for forming the cutting insert comprises the
steps of placing a powdered material into a die and pressing the
powdered material in the die to achieve a form having a convex
portion on the rake face and at least one substantially flat
clearance face having a positive clearance angle. Next, the form is
removed from the die and sintered.
Inventors: |
Waggle; James M. (Derry,
PA) |
Assignee: |
Kennametal Inc. (Latrobe,
PA)
|
Family
ID: |
25050039 |
Appl.
No.: |
09/757,996 |
Filed: |
January 10, 2001 |
Current U.S.
Class: |
407/114;
407/116 |
Current CPC
Class: |
B23B
27/141 (20130101); Y10T 407/245 (20150115); B23B
2200/0423 (20130101); B23B 2200/0438 (20130101); B23B
2200/201 (20130101); B23B 2200/0476 (20130101); Y10T
407/235 (20150115); B22F 2005/001 (20130101); B23B
2200/0452 (20130101); B23B 2200/0457 (20130101); B23B
2233/20 (20130101) |
Current International
Class: |
B23B
27/14 (20060101); B23B 027/22 (); B23P
015/28 () |
Field of
Search: |
;407/113,114,115,116,117,118,119 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Tsai; Henry W. H.
Attorney, Agent or Firm: Meenan; Larry R.
Claims
What is claimed is:
1. A cutting insert comprising: a rake face, a seating surface and
a plurality of flank faces extending between the rake face and the
seating surface, at least one cutting edge defined by the
intersection of the rake face and at least one of the flank faces;
wherein the rake face has a positive rake face angle .beta. and
includes a convex portion adjacent to the at least one cutting edge
and the at least one flank face includes a substantially flat
clearance face having a positive clearance angle adjacent to the at
least one cutting edge and wherein a portion of the at least one
cutting edge is of a convex shape as defined by the intersection of
the convex portion and the substantially flat clearance face, and
wherein a chamfered corner is provided between all adjacent cutting
edges.
2. A cutting insert according to claim 1, wherein the rake face has
a topography forming a chip breaking surface.
3. A cutting insert according to claim 2, wherein the clearance
face is one of a plurality of clearance faces each having a
positive clearance angle, each one of the clearance faces being
formed by a flat surface.
4. A cutting insert according to claim 3, wherein a cutting edge is
formed at the intersection between the surface having the convex
portion and the clearance face, a convex wiper cutting edge being
formed on the cutting edge.
5. A cutting insert according to claim 4, wherein the cutting edge
is a major cutting edge and a minor cutting edge is formed at an
intersection between the surface having the convex portion and a
different one of the plurality of clearance faces.
6. A cutting insert according to claim 1, wherein the cutting
insert has a substantially square cutting geometry.
7. A cutting insert according to claim 1, wherein the cutting
insert has a substantially octagonal cutting geometry.
8. A cutting insert according to claim 1, wherein the cutting
insert has a substantially pentagonal cutting geometry.
9. A cutting insert comprising: a rake face having a convex
portion; a plurality of flank faces, including clearance faces, at
least one of the clearance faces having a positive clearance angle;
at least one major cutting edge formed at an intersection between
the rake face and one of the plurality of clearance faces; at least
one minor cutting edge formed at an intersection between the rake
face and a different one of the plurality of clearance faces; and
at least one wiper cutting edge having a convex wiper cutting edge
formed on the at least one of the minor cutting edge and
optionally, major cutting edge, wherein a chamfered corner is
provided between all adjacent cutting edges wherein the rake face
has a positive rake face angle .beta..
10. A cutting insert according to claim 9, wherein the rake face
has a chip breaking surface.
11. A cutting insert according to claim 9, wherein the cutting
insert has a substantially square cutting geometry.
12. A cutting insert according to claim 9, wherein the cutting
insert has a substantially octagonal cutting geometry.
13. A cutting insert according to claim 9, wherein the cutting
insert has a substantially pentagonal cutting geometry.
Description
FIELD OF THE INVENTION
The present invention pertains to a cutting insert to be used in
cutting tools during machining operations. More particularly, the
present invention relates to an insert having a convex wiper
cutting edge defined between two surfaces wherein one of the
surfaces is a clearance face having a positive clearance angle.
BACKGROUND OF THE INVENTION
It is well known to provide cutting inserts with wiper cutting
edges by creating a straight edge or facet on the insert cutting
edge. This facet is located after the major cutting edge and
creates an improved surface finish by reducing the magnitude of the
high points on the machined surface.
When creating a straight edge or facet on the insert cutting edge,
the width of the facet must be greater than the advance per
revolution to allow the cutting edges to overlap. Moreover, the
spindle must be tilted at a critical angle because excessive
spindle tilt causes the insert to dig into the work surface due to
the sharp ends on the insert. Thus, this configuration does not
allow for the rotational angular tolerance of the insert when
mounted in the insert pocket.
This design has been improved upon by grinding the side surface of
the facet so that it is radiused, thereby creating a radiused wiper
cutting edge. The ground radius allows for the angular tolerance
without having a detrimental effect on the resulting surface finish
by insuring that the ends of the cutting edge do not contact and
scratch the work surface.
Instead of grinding the side surface of the facet, the radius on
the wiper cutting edge can be formed by grinding the top, chip
breaking surface of the insert. An example of such an insert is the
MICRO MILL insert available from Ingersoll as Part No. YCE434-01.
However, this type of insert requires a negative axial rake to
produce the convex wiper cutting edge. In addition, the grinding of
the top surface and the accuracy with which it is ground create
additional manufacturing operations and costs. Thus, it would be
desirable to provide an insert having a generated convex cutting
edge (wiper), or a convex cutting edge (wiper) that is formed
without grinding.
SUMMARY OF THE INVENTION
The present invention is directed towards a cutting insert
comprising a rake face including a convex portion, a flank face
including a clearance face having a positive clearance angle, a
cutting edge formed at an intersection between the rake face and
the flank face, and a convex cutting edge formed on the cutting
edge.
The invention is also directed towards a method for forming a
cutting insert. The method comprises the steps of placing a
powdered material into a die and pressing the powdered material in
the die to achieve a form having a convex rake face and at least
one flank face including a clearance face having a positive
clearance angle. Next, the form is removed from the die and
sintered.
BRIEF DESCRIPTION OF THE DRAWINGS
While various embodiments of the invention are illustrated, the
particular embodiments shown should not be construed to limit the
claims. It is anticipated that various changes and modifications
may be made without departing from the scope of this invention.
FIG. 1 is a perspective view of a cutting insert having a
substantially square cutting geometry and a convex cutting edge in
accordance with the invention.
FIG. 2 is a top plan view of the cutting insert of FIG. 1.
FIG. 3 is a side elevational view of the cutting insert of FIG.
1.
FIG. 4 is a cross section view of the cutting insert taken along
line 4--4 of FIG. 2.
FIG. 5 is an enlarged view of the clearance face and chip breaking
surface of the insert of FIG. 1.
FIG. 6A is an enlarged view of the insert of FIG. 1 performing a
milling or turning operation on a workpiece.
FIG. 6B is an enlarged diagrammatic representation of the working
cutting edges of the insert of FIG. 6A.
FIG. 7 is a perspective view of a cutting insert having a
substantially parallelogram cutting geometry and a convex cutting
edge.
FIG. 8 is a top plan view of the cutting insert of FIG. 7.
FIG. 9 is a side elevational view of the cutting insert of FIG.
7.
FIG. 10 is an end view in elevation of the cutting insert of FIG.
7.
FIG. 11A is an enlarged view of the insert of FIG. 7 performing a
milling or turning operation on a workpiece.
FIG. 11B is an enlarged diagrammatic representation of the working
cutting edges of the insert of FIG. 11A.
FIG. 12 is a perspective view of a cutting insert having a
substantially pentagonal cutting geometry and a convex cutting
edge.
FIG. 13 is a top plan view of the cutting insert of FIG. 12.
FIG. 14 is an enlarged diagrammatic representation of the working
cutting edges of the insert of FIG. 12 during a milling or turning
operation on a workpiece.
FIG. 15 is a top plan view of a cutting insert having a
substantially octagonal cutting geometry and a convex cutting
edge.
FIG. 16 is a side elevational view of the cutting insert of FIG.
15.
FIG. 17 is an enlarged diagrammatic representation of the working
cutting edges of the insert of FIG. 15 during a milling or turning
operation on a workpiece.
FIG. 18 is a perspective view of a cutting insert having another
octagonal cutting geometry and a convex cutting edge.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1-3, there is shown an insert 10. The insert 10
includes a rake face 12, a seating surface 14 and a plurality of
flank faces 16 extending between the rake face and the seating
surface. At least one cutting edge 18 is defined by the
intersection of at least one of the rake faces 12 and at least one
of the flank faces 16.
As shown, the insert 10 includes four cutting edges 18 that are
formed at the intersection between the rake face 12 and four flank
faces 16. Thus, the insert 10, may have a substantially square
cutting geometry. Each of the cutting edges can be indexed into a
working or active position and effectively utilized in a cutting
tool of a type well known in the art.
The at least one rake face 12 includes a convex portion 12a and the
at least one flank face 16 includes a substantially flat clearance
face 16a having a positive clearance angle adjacent to the at least
one cutting edge 18. The rake face 12, or a portion thereof,
preferably includes a chip breaking surface of a type well known in
the art. The intersection of the convex portion and the
substantially flat clearance face defines a portion the at least
one cutting edge of a convex shape. The convex shape portion of the
cutting edge may be useful as a wiper to produce an improved
surface finish on a workpiece 24.
The insert 10 may further include four corner radii or chamfered
corners 20 at the intersection between two adjacent cutting edges
18. It will be appreciated that chamfered corners 20 produce a
finer surface finish on the workpiece 24 than an insert that has a
sharp or flat corner.
The rake face and seating surface 12, 14 of the insert 10 may be
formed with a centrally disposed, substantially planar island 22
which projects above or below the cutting edges 18 by a height, H,
which for example, may be in the range of about 0.05 mm to about
0.40 mm. The island 22 may be used as a clamping surface when the
insert 10 is positioned in the cutting tool. In the alternative, it
will be appreciated that the insert 10 can be provided with a hole,
such as the hole 82 shown, for fixing the insert 70 in the cutting
tool.
As best shown in FIG. 3, the clearance faces 16a are preferably not
perpendicular to the upper and lower surfaces 12, 14, but instead
are inclined at a positive clearance angle, .alpha., (that is, the
angle formed between each clearance face 16a and a plane oriented
parallel to the center axis, A.sub.I, of the insert 10) greater
than 0 degrees so that that the clearance faces 16a converge or
taper inwardly from the rake face 12 to the seating surface 14.
As seen in FIGS. 4 and 5, the rake face 12 includes a convex
portion 12a which slopes away from the cutting edge 18 at a
positive or negative angle or 0 degree angle, .beta.. The convex
portion 12a may, for example have a topography of a conical,
cylindrical, elliptical, or spherical shape. The slope of the
convex portion 12a may gradually increase or decrease as the rake
face 12 approaches the island 22.
During a machining operation, certain cutting edges may be used.
These cutting edges are commonly referred as "working cutting
edges". The insert 10 shown in FIGS. 6A and 6B has two working
cutting edges; a working major cutting edge 18a and a working minor
cutting edge 18b.
The working major cutting edge 18a extends a distance D.sub.1
between two of the chamfered corners 20. The working minor cutting
edge 18b extends a distance D.sub.2 from the intersection of the
working major and minor cutting edges 18a, 18b to another chamfered
corner 20. Portions of the working major and minor cutting edges
18a, 18b that actually engage the workpiece 24 may be defined as
"active cutting edges". For example, as shown in FIGS. 6A and 6B,
an active major cutting edge may extend a distance D.sub.3 from the
intersection of the working major and minor cutting edges 18a, 18b
and away from the working minor cutting edge 18b. An active minor
cutting edge may extend a distance D.sub.4 from the intersection of
the working major and minor cutting edges 18a, 18b and away from
the working major cutting edge 18a.
Referring to FIGS. 6A and 6B, the working major and/or minor
cutting edges 18a, 18b may further include a convex cutting edges
18c and 18d. The convex cutting edges 18c and 18d may be defined by
a portion of the working major and/or minor cutting edges 18a, 18b
that produces a transient and/or machined surface. The convex
cutting edge 18c and 18d is defined by the intersection of the
convex portion 12a of the rake face 12 and the substantially flat
clearance face 16a. The convex cutting edges 18c, 18d have a convex
portion 12a generally defined by a radius, R, as shown in FIG.
3.
It will be appreciated that the convex cutting edges 18c, 18d of
the invention allow the insert 10 to produce an improved surface
finish on the workpiece 24. It will be further appreciated that the
principles of the invention of forming a convex cutting edge
(wiper) by the intersection of a convex portion of the rake surface
and a substantially flat clearance face of the flank surface can be
applied to inserts having any desired cutting geometry and any
desired number of cutting edges.
For example, FIGS. 7-10 illustrate the principles of the invention
being applied to another insert 70 having a substantially
parallelogram shaped geometry. The insert 70 has a rake face 72, a
seating surface 74, and flank faces 76 including four substantially
flat clearance faces 76a. The rake face 72, or a portion thereof,
may include a chip breaking surface.
The insert 70 preferably has four cutting edges 78 that are formed
at the intersection between the rake face 72 and the four flank
faces 76. In addition, the insert 70 may include four corner radii
or chamfered corners 80 formed at the intersection between two
adjacent cutting edges 78. Each of the cutting edges 78 can be
indexed into an active position and effectively utilized in a
cutting tool of a type well known in the art.
The rake face 72 and seating surface 74 of the insert 70 can be
formed with a centrally disposed island, similar to the insert 10
described above. The island may project above or below the cutting
edges 78. The island may be used as a clamping surface when the
insert 70 is positioned in the cutting tool as well known in the
art. Moreover, in an alternate embodiment, the island can be
provided with a hole 82 for fixing the insert 70 in the cutting
tool.
During a machining operation, the insert 70 may include a working
major cutting edge 78a and a working minor cutting edge 78b,
similar to those shown in FIGS. 11A and 11B. The working major
cutting edge 78a may extend a distance D.sub.5 between two of the
chamfered corners 80. The working minor cutting edge 78b extends a
distance D.sub.6 from the intersection of the working major and
minor cutting edges 78a, 78b to another chamfered corner 80.
Portions of the working major and minor cutting edges 78a, 78b that
actually engage the workpiece 84 may be defined as "active cutting
edges". An active major cutting edge may extend a distance D.sub.7
from the intersection of the working major and minor cutting edges
78a, 78b and away from the working minor cutting edge 78b. An
active minor cutting edge may extend a distance D.sub.8 from the
intersection of the working major and minor cutting edges 78a, 78b
and away from the working major cutting edge 78a.
A convex cutting edge may be defined by a portion of the working
major and/or minor cutting edges 78a, 78b that produces a transient
and/or machined surface. The insert shown in FIGS. 11A and 11B has
a convex cutting edges 78c and 78d that are respectively defined by
the active major and minor cutting edges.
The convex cutting edges 78c and 78d are defined by the convex
portion 72a of the rake face 72 and the substantially flat
clearance face 76a. The convex cutting edge 78c has a convex
portion defined by a radius, R.sub.MAJ, as shown in FIG. 9. The
convex cutting edge 78d has a convex portion 72a defined by a
radius, R.sub.MIN, as shown in FIG. 10. The convex cutting edges
78c, 78d of the invention allow the insert 70 to produce an
improved surface finish on the workpiece 84.
FIGS. 12-13 illustrate the principles of the invention being
applied to an insert 90 having a substantially pentagonal shaped
cutting geometry. The insert 90 has a rake face 92, a seating
surface 94, an end surface 95, and four flank faces 96 including
four substantially flat clearance faces 96a. The rake face 92, or a
portion thereof, may define a chip breaking surface. The end
surface 95 is provided for fixing the insert 90 in a cutting tool
of a type well known in the art.
The insert 90 preferably has four cutting edges 98 that are formed
at the intersection between the rake face 92 and the four flank
faces 96. In addition, the insert 90 may include corner radii or
chamfered corners 100 formed at the intersection between two
adjacent cutting edges 98. The cutting edges 98 are provided for
right and left-handed operations.
The rake face 92 and the seating surface 94 of the insert 90 can be
formed with a centrally disposed island, similar to the inserts 10
and 70 above. The island may project above or below the cutting
edges 98. The island may be used as a clamping surface when the
insert 90 is positioned in the cutting tool. Moreover, the insert
90 can be provided with a hole, such as the hole 102 shown, for
fixing the insert 90 in the cutting tool.
During a machining operation, the insert 90 may include a working
major cutting edge 98a and a working minor cutting edge 98b,
similar to those shown in FIG. 14. The working major cutting edge
98a may extend a distance D.sub.9 between two of the chamfered
corners 100. The working minor cutting edge 98b may extend a
distance D.sub.10 from the intersection of the working major and
minor cutting edges 98a, 98b to another chamfered corner 100. An
active major cutting edge may extend a distance D.sub.11 from the
intersection of the working major and minor cutting edges 98a, 98b
and away from the working minor cutting edge 98b. An active minor
cutting edge may extend a distance D.sub.12 from the intersection
of the working major and minor cutting edges 98a, 98b and away from
the working major cutting edge 98a. A convex cutting edge may be
defined by a portion of the working major and/or minor cutting
edges 98a, 98b that produces a transient and/or machined surface.
The insert shown in FIG. 14 has a convex cutting edge 98c defined
by the active minor cutting edge.
The convex cutting edge 98c is defined by the intersection of the
convex portion 92a of the rake face 92 and the substantially flat
clearance face 96a. The convex cutting edge 98c of the invention
allows the insert 90 to produce an improved surface finish on the
workpiece 104.
FIGS. 15-16 illustrate the principles of the invention being
applied to yet another insert 120. Similar to the insert 10 above,
this insert 120 has a substantially square cutting geometry. The
insert 120 has a rake face 122, a seating surface 124, eight flank
faces 126 including four clearance faces 126a. The rake face 122,
or a portion thereof, may include a chip breaking surface. Although
only three flank faces 126 are shown in FIG. 16, the opposite side
of the insert 120 has identical flank faces. The clearance faces
126a are preferably substantially flat. The insert 120 preferably
has eight cutting edges 128 that are formed at the intersection
between the rake face 122 and the eight flank faces 126.
The rake face 122 and seating surface 124 of the insert 120 can be
formed with a centrally disposed island, similar to the inserts 10,
70, and 90 above. The island may be used as a clamping surface when
the insert 120 is positioned in the cutting tool. Moreover, the
insert 120 can be provided with a hole, such as the hole 132 shown,
for fixing the insert 120 in the cutting tool.
During a machining operation, the insert 120 may include a working
major cutting edge 128a and a working minor cutting edge 128b,
similar to those shown in FIG. 17. The working major cutting edge
128a may extend a distance D.sub.13 from and away from the working
minor cutting edge 128b. The working minor cutting edge 128b
extends a distance D.sub.14 from and away from the working major
cutting edge 128a. An active major cutting edge may extend a
distance D.sub.15 along the working major cutting edge 128a. An
active minor cutting edge may extend a distance D.sub.16 along the
working minor cutting edge 128b. A convex cutting edge 128c may be
defined by the active minor cutting edge.
The convex cutting edge 128c is defined by the intersection of the
convex portion 122a of the rake face 122 and the substantially flat
clearance face 126a. The convex cutting edge 128c of the invention
allows the insert 120 to produce an improved surface finish on the
workpiece 134.
FIG. 18 illustrates the principles of the invention being applied
to still another insert 140. The insert 140 may include a rake face
142, a seating surface 144, and flank faces 146 including clearance
faces 146. The rake face 142, or a portion thereof, preferably
defines a chip breaking surface. The clearance faces 146 are
preferably substantially flat. The insert 140 may include eight
cutting edges 148 that are formed at the intersection between the
rake face 142 and the eight flank faces 146. Thus, the insert 10
may have a substantially octagonal cutting geometry. Each of the
cutting edges 148 can be indexed into an working or active position
and effectively utilized in a cutting tool of a type well known in
the art.
The insert 140 may further include eight corner radii or chamfered
corners 150 at the intersection between two adjacent cutting edges
148.
The rake face 142 and seating surface 144 of the insert 140 may be
formed with a centrally disposed, substantially planar island 152.
The island 152 may be used as a clamping surface when the insert
140 is positioned in the cutting tool.
The rake face 142 may have a convex portion 142a of a conical,
cylindrical, elliptical, or spherical topography. Each clearance
face 146a preferably has a positive clearance angle. A convex
cutting edge 148a may be defined by a portion of each cutting edge
148.
It should be understood that the radius of the convex portion of
the convex cutting edge may vary. In fact, the radius may be so
great that the convex portion of the convex cutting edge may, for
example, from a cursory inspection, appear to be straight. There
are no particular ranges set for the radii, R, R.sub.MIN,
R.sub.MAJ, set forth above. Values for the radii are based on such
variables as the axial and radial rake of the insert, the
rotational pocket tolerance of the insert, the feed of the
workpiece, the clearance angle on the insert, the chip breaker land
angle, and the cutting edge of the insert. This list of variables
is provided for illustrative purposes and is not intended to be
exhaustive. The radii are intended to be calculated independently
of one another.
It should also be understood that principles of the invention are
not limited by the cutting geometry of the inserts shown, and that
the principles of the invention can be practiced with inserts
having any cutting geometry. For example, although not shown, any
of the cutting edges may be chamfered to form a cutting insert with
a land on the cutting edge.
It should be further understood that the entire rake face need not
be convex but rather a portion or portions of the rake face may be
convex.
It will be appreciated that the convex cutting edges of the present
invention can be formed without grinding. For example, the convex
portion 12a of the rake face 12 has a topography that can be formed
by sintering a convex conical, cylindrical, elliptical, or
spherical shape on the rake face 12 of the insert 10. The clearance
faces 16a can be formed by pressing or grinding a substantially
flat surface to enable the insert 10 to properly seat when
positioned in the cutting tool.
An insert according to the present invention can be formed
according to the following method steps. First, a powdered material
may be placed into a die and pressed in the die to achieve a
desired form. Subsequently, the form may be removed and sintered,
that is, cured in a furnace. The sintered form may be smaller than
the form prior to being sintered. Hence, the size of the die may
have to accommodate shrinkage.
The foregoing method may not produce a cutting insert within
desired tolerances. Hence, the resultant form or portions thereof
may have to be ground to produce a cutting insert within the
desired tolerances. It should be understood, however, that the die
may be shaped to produce the convex cutting edge and clearance
faces having positive clearance angles without grinding the
insert.
The patents and publications referred to herein are hereby
incorporated by reference. Having described presently preferred
embodiments the invention may be otherwise embodied within the
scope of the appended claims.
* * * * *